The present invention relates generally to syringes, and more particularly to an improved syringe guard for a unit dose cartridge or pre-filled syringe and including a shield for covering the needle thereof after medication is dispensed from the syringe.
Medication is often dispensed using a unit dose medical cartridge, such as an ampule, vial or syringe, and a syringe holder, injector or adapter. The cartridge typically has a barrel with a needle at one end and a plunger at the other end. Such cartridges are often referred to as xe2x80x9cpre-filled syringesxe2x80x9d because they contain a specific dosage or volume of medication when they are initially provided, as compared to conventional syringes which are furnished empty and filled by the user prior to use. Alternatively, the medical cartridge may include a rubber stopper instead of a needle, or may include a piston rather than a plunger on the other end. The syringe adapter is typically a hollow body adapted to hold the cartridge, including a plunger to engage and move the piston in the cartridge.
Because of the threat of communicable diseases, a number of syringes and adapters have been developed to prevent accidental needle sticks or inadvertent reuse of needle devices. Many of these devices, however, are not easy to use or are complicated to manufacture, resulting in less effective disposable syringe devices.
For example, U.S. Pat. No. 5,569,211 discloses a syringe that allows the needle of the syringe to be withdrawn into the barrel of the syringe after medication is dispensed from it. This device, however, is a specially designed substitute for a conventional syringe, and cannot be used to hold commercially available pre-filled syringes.
U.S. Pat. No. 5,522,812 discloses a complicated syringe shield device for holding a conventional cartridge not having its own needle. The device has a number of complicated parts, including a cylindrical body, a double needle assembly, a cylindrical shield, a special collar piece allowing the shield to be drawn over the needle and locked, and a plunger assembly, resulting in a device that is potentially difficult and expensive to manufacture. The device also requires two hands to operate, one to hold the body, and one to rotate the shield into the locked position, which may be inconvenient to the medical professional using the device.
Another consideration with unit dose cartridges and pre-filled syringes is that they are often made from glass, particularly for holding certain vaccines or biotech drugs where concern about micro-organisms or other contaminants is most critical. Glass cartridges and pre-filled syringes are very fragile and often break during transportation or use. Some existing adapters may not adequately protect the syringe contained therein from such risks. Others provide greater protection for the cartridge, but may obstruct the professional""s view of the syringe when the device is being used, hampering monitoring of the medication being delivered.
Therefore, there is a need for an improved safety syringe which is inexpensive and simple to manufacture.
In addition, there is a need for a safety syringe guarding mechanism which provides improved protection for the cartridge or pre-filled syringe therein, but allows effective observation of the syringe and the medication being dispensed.
The present invention is directed to a guard or adapter for a medical cartridge, such as a unit dose cartridge or pre-filled syringe, that is used to inject medication or other drugs into a patient. Generally, the guard comprises two parts, namely a housing or body for receiving and holding the cartridge, and a protective case or shield slidably attached to the body. In addition, for a cartridge provided without its own plunger, an embodiment of the guard includes a finger grip plug that is attached to the body and a plunger connectable to the piston of the cartridge. The various parts are generally molded from a suitable plastic, such as polypropylene, synthetic resinous polymers of butadiene and styrene, or polycarbonate, having a clear finish.
The body generally includes two elongate rails or similar structures defining a substantially rectangular shape, having a cavity therein adapted to receive a medical cartridge or a pre-filled syringe. The body has an open proximal end communicating with the cavity, a distal end with an opening through it, and possibly a collar molded to the distal end. The body may also include a plurality of tabs or ribs extending along a portion of the cavity adapted to engage the barrel of a cartridge received therein.
The protective case or shield is a tubular member adapted to slidably fit on the body, having open proximal and distal ends. One or more elongate windows are formed in the shield, allowing observation of the cartridge or pre-filled syringe held within the body. One or more windows, preferably the same windows used for viewing the cartridge, also cooperate with a stop tab or tabs molded on the body, thereby limiting the relative sliding relationship of the shield and the body. In addition, the shield includes a set of detents, preferably comprising a pair of detent arms and protruding detents molded into the proximal end of the shield. The detents cooperate with one or more sets of detent pockets molded into the body to lock the shield in relation to the body.
The shield is generally provided pre-assembled on the body, preferably by inserting the body into the shield until the stop tabs on the body communicate with the elongate windows on the shield. The shield may then slide in relation to the body between a proximal or unguarded position and a distal or guarded position, defined by the length of the windows in the shield. The guard is generally provided with the shield in the proximal or unguarded position, wherein the stop tabs abut the distal edges of the windows. Alternatively, the proximal travel of the shield may be limited by the detent arms abutting a finger grip on the body. In the unguarded position, the detents on the shield preferably engage a set of proximal detent pockets on the body, holding the shield in relation to the body.
Generally, after the cartridge or pre-filled syringe in the guard has been used to deliver its medication, the shield is moved distally until it reaches the guarded position. In the guarded position, the stop tabs on the body abut the proximal edges of the windows, preventing further distal movement. As the shield is moved, the detents on the shield leave the proximal detent pockets, preferably because of sloping edges on the proximal detent pockets, and slide along the body until they enter a set of distal detent pockets when the shield reaches the guarded position. The distal detent pockets may have blunt or oblique proximal edges, which prevent the shield from being returned proximally, and thereby substantially lock the shield in the guarded position for disposal. Preferably, the proximal edges of the detent pockets are inclined at an angle corresponding substantially to the proximal edges of the detents to maximize bearing surface engagement therebetween.
In a first preferred embodiment, the guard has only two parts, namely a body and a shield, which are pre-assembled in the unguarded position ready to receive a cartridge. In this embodiment, the body includes a finger grip integrally molded onto its proximal end, preferably defining a xe2x80x9cTxe2x80x9d shape, having locking detents formed on the finger grip. A cartridge, preferably and typically a conventional unit dose pre-filled syringe including a needle and needle cover on its distal end and a plunger and flange on its proximal end, is inserted into the proximal end of the body until it is fully encapsulated within the cavity. Once fully inserted, the proximal end of the pre-filled syringe engages the locking detents on the finger grip, substantially permanently locking the pre-filled syringe into the guard. Once locked into the guard, the needle and its cover on the pre-filled syringe extend at least partially through the distal openings in the body and shield and preferably beyond their distal ends.
After medication is dispensed, the shield is slid into the guarded position, using one or two hands, preferably only requiring one hand. During use, the index and middle fingers are generally placed on the finger grip adjacent the shield, while the thumb directs the plunger on the pre-filled syringe. To move the shield, the free hand may be used to slide the shield, or the thumb and ring finger of the same hand may be moved to the finger grip to hold the body. The index and middle fingers may hold the sides of the shield and move it distally, thereby sliding the shield until it is locked in the guarded position.
In a second preferred embodiment, the guard includes an attachable finger grip plug and a plunger, in addition to the body and shield. The plunger, with or without a thumb ring, a button plunger, or a xe2x80x9cTxe2x80x9d handle on one end, is attachable to the piston of a conventional unit dose cartridge. The finger grip plug may include a finger grip thereon, such as a pair of wings or an octagonal flange. The finger grip plug and the proximal end of the body include cooperating members for locking the finger grip section to the body and preventing the cartridge within the body from moving substantially axially. Preferably, the finger grip plug has locking detents thereon, and the proximal end of the body includes an annular-shaped collar having tapered pockets therein adapted to receive the locking detents.
The body and shield are generally provided pre-assembled in the unguarded position, as previously described, with the finger grip plug and plunger furnished separately. A cartridge, preferably a unit dose glass cartridge having a needle and needle cover on its distal end and a piston in its proximal end, is inserted into the proximal end of the body until it is fully encapsulated within the cavity. Once fully inserted, the finger grip plug is attached to the body, by aligning the locking detents on the finger grip section with the tapered pockets in the collar. The locking detents are inserted into the pockets until they engage, substantially permanently and/or releasably enclosing the cavity and encapsulating the cartridge therein. In addition, the detents on the finger grip plug may substantially engage the proximal end of the cartridge, thereby preventing the needle on the cartridge from withdrawing proximally into the body during use.
In addition, the plunger may include a radially extending detent or tab that is compressed when the plunger is directed into the finger grip plug. The tab resiliently returns to its extended position once the plunger is fully inserted into the finger grip plug, thereby preventing the plunger from being removed therefrom.
Once the guard, cartridge and finger grip plug are assembled, the needle and needle cap on the cartridge extend through the distal ends of the shield and body. The plunger is attached to the piston in the cartridge, such as by a threaded bore on the distal end of the plunger which is adapted to screw into a threaded nipple on the piston. The device is then ready to be used to deliver medication to a patient. After medication is dispensed, the shield is slid into the guarded position, as with the first embodiment, with one or two hands.
In additional preferred embodiments, the syringe guard includes a body and a sliding shield similar to that described above, for holding a unit dose pre-filled syringe having its own plunger. In particular, the guard includes a mechanism on the proximal end of the body, preferably on or within the finger grip, for substantially permanently (or releasably under certain conditions) securing the syringe within the guard and substantially preventing distal and/or proximal movement of the syringe received therein. More preferably, the locking mechanism requires the syringe to be inserted into the guard in a predetermined orientation, thereby facilitating viewing of a label or the like on the cartridge through the windows in the guard.
For example, the mechanism may include a clip or ring for clasping the finger grip and the proximal flange of the syringe together. Preferably, a pair of clips are provided which slide over and engage the distal and proximal surfaces respectively of the finger grip and the flange of the syringe.
Alternatively, the body may include an annular member within the open end thereof for creating an interference fit with the barrel of the syringe inserted into the guard. Preferably, an annular ring extends radially into the cavity, thereby frictionally engaging an enlarged proximal end of the syringe directed into the cavity to prevent removal of the syringe.
In a further alternative, the finger grip has a substantially rectangular shape including a recess in the proximal end for receiving the flange or the proximal end of the pre-filled syringe. One or more tabs or detents extend into the recess from one or more walls of the finger grip for engaging the flange of the syringe to secure it within the guard.
Alternatively, the finger grip may include a latch or cover for enclosing the recess once a syringe is inserted therein, the latch preferably being attached to the finger grip by a hinge along a wall defining the recess. Once the flange of the syringe is directed into the recess, the latch is closed, preferably engaging a tab within the recess to prevent the latch from coming loose and releasing the syringe. The latch also preferably includes an aperture for accommodating a plunger of the syringe received within the body.
In a final preferred embodiment, the syringe guard is adapted to receive relatively small cartridges or pre-filled syringes, for example a 0.5 mL unit dose pre-filled syringe including a rigid nose shield or needle cap having a diameter larger than the barrel of the syringe. The guard includes a body having a mechanism in its proximal end for lockably engaging the proximal end of the pre-filled syringe received therein, such as those described above. In addition, the body includes one or more semi-rigid members, for example pairs of tabs or longitudinal ribs, extending along the cavity for engaging the barrel of the syringe. The body may also include one or more lead-in ribs at or near the proximal end of the cavity for guiding the pre-filled syringe during insertion. When the syringe is inserted into the body, the cap engages the tabs as it enters the cavity. The tabs are forced radially out to allow the cap to pass through the cavity. Once the cap extends beyond the proximal end of the body, the tabs resiliently return to abut or engage the wall of the barrel, thereby preventing substantial lateral movement of the syringe within the body during use. The tabs also preferably prevent the rails of the guard body from being compressed after use to prevent inadvertent release of the cooperating locking detents on the shield and body.
As will be understood, the present invention provides an improved guard for medical cartridges or pre-filled syringes that may include as few as two parts, but generally has no more than four parts. The device may be used for a wide variety of conventional prepackaged medications or drugs, such as anesthesia, anti-thrombotic drugs, biological drugs or vaccines, for use within the medical and/or dental fields, where the cartridge or pre-filled syringe is generally disposed of after a single use. Because the device is relatively simple, the parts may be provided in standard configurations. For example, a single shield design may be provided that fits on a variety of bodies for receiving cartridges or pre-filled syringes made by different manufacturers. In addition, the distal openings in the body and/or the shield may be provided in a plurality of sizes to accommodate a variety of needle caps, luer adapters and the like. Thus, the guard may be more easily mass produced, reducing manufacturing costs, and thereby providing a more competitively priced disposable syringe guard.
In addition, the rectangular configuration of the present device provides improved rigidity, thereby affording greater protection to the cartridge held in the guard. Although the cartridge or pre-filled syringe is fully encapsulated within the guard, the windows in the guard allow the medical or dental professional to effectively monitor the cartridge or pre-filled syringe and the medication being delivered.
Finally, the slidable shield and cooperating detents allow the user to operate the guard using only one hand, thereby allowing their other hand to be free to perform other necessary tasks, such as restraining a young patient or providing improved access to the target region for the needle. Once the shield is locked in the guarded position, the device may be disposed of safely if used properly, substantially eliminating concerns that the needle may become exposed and cause an accidental stick.
Accordingly, it is a principal object of the present invention to provide an improved unit dose syringe device that is easy to manufacture and convenient to use.
It is also an object to provide an improved syringe guard that affords improved protection for a cartridge or pre-filled syringe encapsulated therein but still allows effective monitoring of the medication being dispensed.
Other objects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.